*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
.avatar{
    width: 100px;
    height: 100px;
    border-radius: 50%;
    background-color: #f00;
    overflow: hidden;
    animation: rotate 5s linear infinite;
}
@keyframes rotate{
    100%{
        transform: rotate(360deg);
    }
}